Blade locking means



- g- 1958 e. B. MURPHY BLADE LOCKING MEANS Filed Jan. 21, 1955 INVENTOR GE PGEB. MURPHY 5 M ATTORNEY i w z F/G. Z

UnitedStates Patent Ofiice 2,847,187 Patented Aug. 12, 1958 BLADE LOCKING MEANS George B. Murphy, Manchester, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application January 21, 1955, Serial No. 483,325

9 Claims. (Cl. 253-77) This invention relates to blade locking means for retaining compressor or turbine blades within the axially extending slots in the supporting rotor.

Locking devices having bendable parts are well known, as shown for example, in Kroon 2,434,935 and Comery 2,641,443. In each of these patents the lock is of necessity made of a material that is readily bendable into the locking configuration after the blade and lock are assembled on the rotor but which will stay in the locking configuration after being bent. The principal feature of this invention is a blade lock that requires no bending or other forming after assembly between the blade and the supporting rotor.

The co-pending application of Normal L. Turnbull, Serial No. 483,257, filed concurrently herewith discloses a lock having a resilient tab projecting from the plane of the main part of the lock and engaging a notch in the blade for holding the latter in position in the supporting rotor. The present invention is, in certain respects, an improvement on the invention disclosed in this co-pending application, in that it provides for .insertion of the blade from either end of the slot and also provides for removal of the blade from either end of the slot. This feature is particularly advantageous in certain multi-stage rotors where the spacing between adjacent rows of blades may be toonarrow to permit removal of the blades at one side of the supporting disc.

A further feature of this invention is a blade lock having a projection located between the ends of the lock with the lock itself resilient enough to be bent out of the normal plane of the locking piece. With this arrangement, the blade root and cooperating rotor disc are so constructed as to permit the flexing of the locking strip during insertion or removal of the blade.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

Fig. l is a fragmentary sectional view of the blade lock in operative position.

Fig. 2 is a view similar to Fig. 1 showing the blade partly assembled on the rotor.

Fig. 3 is a view of the parts of Fig. 1 in prospective and spaced redially apart to show the construction.

Fig. 4 is a plan view of the lock.

Fig. 5 is a side elevation of the lock.

Fig. 6 is a sectional view substantially along the line 6-6 of Fig.1.

Fig. 7 is a fragmentary sectional view similar to Fig. 1 showing a modification.

The lock is shown in connection with the attachment of a compressor blade to a supporting rotor disc. As best shown in Figs. land 3, the blade supporting rotor or rotor member 2 is in the form of a disc having a side peripheral flange 4 in which are formed a plurality of axially extending slots 6, each of which receives the root 8 of one of the blades or blade members 10. In the arrangement shown, the slot 6 is dovetail in shape and the bladeroot is similar in shape. Each slot 6 has a narrow portion 12 radially outward of the base thereof so that the blades are retained radially in position within the slots. The particular configuration of the blade root and slot is not critical. The base surface 14 of the slot is preferably flat from end to end and the base surface 16 of the blade root, when positioned within the slot, is spaced from the surface 14 a suflicient distance to receive the blade lock 18 therebetween, as best shown in Figs. 1 and 6.

With reference to Figs. 4 and 5, the lock 18 has a main portion located in the space between the base surfaces 14 and 16 and in the form of a substantially flat strip of material several times wider than its thickness being preferably nearly the width of the base surface 14 of the slot. At opposite ends of the main portion, the lock has downwardly extending tabs 20 and 22 which are preferably the full width of the strip of the material. These tabs overlie the end surfaces of the peripheral flange on the rotor, as best shown in Fig. l. The main portion of the strip'is resilient and may have an upward bow between its ends when in the unattached position of Figs. 4 and 5. This how, which is from end to end, is at right angles to the plane of the strip, as will be apparent. Between the ends of the strip and preferably substantially midway of the ends, the strip has an ofiset 24 or pro jection extending transversely of the strip. This offset is arcuate in the longitudinal dimension of the strip, as shown in Fig. 5 and is received, when the blade is assembled with the rotor and lock, in a correspondingly shaped notch or recess 26 extending transversely of the base surface of the root. The recess 26 is also arcuate in the longitudinal dimension of the root, as shown. The entire strip is made resilient so that when the blade and locking piece are assembled on the rotor, as shown in Fig. l, the projection 24 will be urged into the notch or recess In the assembly, the locking piece is placed in the base of the slot, as shown in Fig. 2, and the blade root is then inserted at one end of the slot and is moved axially into the completely assembled position of Fig. 1. During this insertion of the blade, the central portion of the locking strip 18 is deflected downwardly into a notch or recess 28 provided in the base surface 14 of the slot 6. This notch 28, as seen in Figs. 1 and 2, is shallow at the ends and deeper in the middle, being radially deep enough directly beneath the projection to accommodate the full height of the projection 24. With this notch 28 provided in the rotor disc, it is possible to move the blade into the fully assembled position of Fig. 1, at which time the resiliency of the strip will move the projection 24 into the recess 26 and effectively prevent unintentional axial movement of the bladewith respect to the disc. A blade may be removed from the disc by axial pressure on the blade without damage to the lock, but it will be apparent that the force necessary to disengage the arcuate projection 24 from the notch 26 is obviously greater than any of the normal forces acting on the blade while it is in operative position within the axial flow compressor or turbine.

For manufacturing purposes, where it may be difficult to machine the recess 28 for the full width of the base surface 14, the central portion of the blade lock may be reduced in width, as shown in Fig. 4, so that it will fit within a narrower recess 28. When this is done, the end portions of the strip are still retained as wide as possible in order to prevent twisting of the lock within the clearance space between the root and base of the slot.

Instead of forming a groove in the base of the slot, the bladeroot 8' may be so dimensioned, as shown in Fig. 7, that the radial clearance between the base surface 16' of the root and the base surface 14 of the slot is enough to clear the offset 24' in the blade lock 18' when the lock is resting flatwise on the surface 14 When this arrangement is used the blade lock must be bowed enough to assure the retention of the offset 24' in the notch or recess 26 in the root.

It is to be understood that "the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure fromits spirit as defined by the following claims.

1. In elastic fluid apparatus, a disc member having root receiving slots extending transversely of said member at its periphery, and blade members having roots engaging in said slots, said roots and slots interlocking to prevent radial movement of said blades outwardly of the disc, the base surface of each root being spaced from the base surface of the slot to provide a clearance space, the base surface of one of said cooperating blade and disc members having a notch therein, in combination with locking means in the form of a resilient strip of material in said clearance space, said strip having a tab at each end out of the plane of the strip and engaging the ends of the other of said members, and a projection on the strip between its ends for engagement in said notch, said projection being resiliently urged into said notch by the resiliency of the strip, the base surface of said other of said members being recessed between its ends and radially opposite to the projection on the strip to permit deflection of the strip during assembly of the blade.

2. In elastic fluid apparatus, a disc member having root receiving slots extending transversely of said member at its periphery, and blade members having roots engaging in said slots, said roots and slots interlocking to prevent radial movement of said blades outwardly of the disc, the base surface of each root being spaced from the base surface of the slot to provide a clearance space, the base surface of one of said cooperating blade and disc members having a notch therein, in combination with locking means in the form of a resilient strip of material in said clearance space, said strip having a tab at each end out of the plane of the strip and engaging the ends of the other of said members, and a projection on-the strip between its ends for engagement in said notch, said projection being integral with and projecting rigidly from the strip and being urged into said notch by the resiliency of said strip when the latter is in normal position in said clearance space, said clearance .space being of sufficient dimension at least radially opposite to the projection on the strip to permit deflection of the strip as the projection engages the other member during assembly of the blade.

3. In elastic fluid apparatus, a disc member having root receiving slots extending transversely of said member at its periphery, and blade members having roots engaging in said slots, said roots and slots interlocking to prevent radial movement of said blades outwardly of the disc, the base surface of each root being spaced from the base surface of the slot to provide a clearance space, the base surface of one of said cooperating blade and disc members having a notch therein, in combination with locking means in the form of a resilient strip of material in said clearance space, said strip having a tab at each end out of the plane of the strip and engaging the ends of the other of said members, and a projection on the strip between its ends for engagement in said notch, said projection being arcuate and extending transversely across the strip between opposite side edges and being resiliently urged into said notch by the resiliency of said strip, the radial dimension of the clearance space at least adjacent the projection being greater than the height of the projectiOn and the thickness of the strip to provide for deflection of the strip during assembly or disassembly of the blade and rotor disc.

4. In elastic fluid apparatus, a disc member having root receiving slots extending transversely of said member at its periphery, and blade members having roots engaging in said slots, said roots and slots interlocking to prevent radial movement of said blades outwardly of the disc, the base surface of each root being spaced from the base surface of the slot to provide a clearance space, the base surface of one of said members having a notch therein, in combination with locking means in the form of a silient strip of material in said clearance space, said strip having a tab at each end out of the plane of the strip and engaging the ends of the other of said members, and a projection on the strip between its ends for engagement in said notch, said projection being arcuate and extending transversely across the strip between opposite side edges, said projection being resiliently urged into said notch by the resiliency of the strip, the base surface of said other of said members being recessed between its ends and radially opposite to the projection on the strip to permit deflection of the strip during assembly of the blade.

5. For use in turbine or compressor rotors having a row of rooted blade members whose roots are disposed in transversely extending slots in the periphery of the rotor member, a locking piece for securing a blade member axially in its slot in the rotor member comprising a flat resilient strip of material having a main portion extending through said slotand having its ends extending beyond said slot and at a substantial angle to said strip to engage the end walls of one of said members, said main portion having a projection therein between its ends, the other of said members having a recess, said projection, when the piece is assembled in a rotor, extending into the recess in the other of said members, said slot being deep enough adjacent to the projection to provide for deflection of said main portion and projection during assembly of the members, the resiliency of the main portion of the strip urging the projection intotherecess.

6. For use in a turbine or compressor rotor member having a row of rooted blade members whose roots are disposed in transversely extending slots in the periphery of the rotor member, a locking piece for securing a blade member in its slot in an associated rotor member comprising a flat resilient strip of material having a main portion extending through said slot and having its ends extending beyond said slot and at a substantial angle to said strip to engage the end walls of one of said members, said main portion having a projection thereon between its ends, the other of said members having a recess, said projection, when the piece is assembled in a rotor, extending into the recess in the other of said members, said slot having a depth at least as great as the height of the projection adjacent to said projection to provide for deflection of said main portion and projection during assembly of the parts, said main portion being resilient and bowed between its ends in the direction of the projection, the resiliency of the main portion of the strip urging the projection into the recess.

7. For use in a turbine or compressor rotor construction having a rotor and a row of rooted blades whose roots are disposed in transversely extending slots in the periphery of the rotor, each blade having a recess in the base of the root and the rotor having a recess in the slot radially opposite to said recess in the blade root, a locking piece for securing one of the blades in its'slot in the rotor, said locking piece comprising a flat strip of resilient material having a main portion extending through said slot and having its ends extending beyond said slot and at a substantial angle to said trip and engaging the end walls of said rotor when assembled, said main portion having a projection thereon extending into the recess in the blade, the recess in said rotor being deep en'ough'to provide for deflection of said main portion and the projection thereon during assembly of the blade in the rotor.

8. In elastic fluid apparatus, a rotor disc having root receiving slots extending transversely of the-disc at its periphery, and blades having roots engaging 'in said slots, said roots and slots interlocking to prevent radial movement of said blades outwardly of said disc, the base surface of the root having a transverse notch'therein between its ends and being spaced from the base surface of the slot to provide a clearance space, in combination with locking means for each blade including a resilient strip of material positioned in said clearance space, said strip having at least one tab projecting from each end and out of the plane of the strip to engage opposite sides of the disc and a transversely extending projection on the strip in a position to engage said notch, said projection being arcuate in the longitudinal dimension of the strip and being resiliently retained in the notch by the resiliency of said strip, the radial dimension of the clearance space at least adjacent the projection being greater than the height of the projection and the thickness of the strip to provide for deflection of the strip during assembly or disassembly of the blade and rotor disc.

9. In elastic fluid apparatus, a rotor disc having root receiving slots extending transversely of the disc at its periphery, and blades having roots engaging in said slots, the base surface of the root having a transverse notch therein between its ends and being spaced from the base surface of the slot to provide a clearance space, in combination with locking means for each blade including a strip of resilient material positioned in said clearance space, said strip having at least one tab projecting from each end and out of the plan-e of the strip to engage opposite sides of the disc and a transversely extending projection on the strip in a position to engage said notch, said projection being arcuate and being resiliently retained in the notch by the resiliency of said strip, the base surface of the slot being recessed between its ends and radially opposite to said projection for deflection of the strip with the projection during assembly of the blade with the locking means and rotor.

References Cited in the file of this patent UNITED STATES PATENTS 2,434,935 Kroon Ian. 27, 1948 2,641,443 Comery June 9, 1953 2,643,853 Redding June 30, 1953 FOREIGN PATENTS 643,914 Great Britain Sept. 27, 1950 1,062,938 France Dec. 9, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,847,187 August 12, 1958 George E Murphy It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 64, claim '7, for "trip" read strip e Signed and sealed this 4th day of November 1958 SEAL 1ttestz KARL H, AXLINE ROBERT C. WATSON Attesting Oificer Commissioner atents 

